Mpg goes down while idle

[AnthonyA1234]

Does this happen to anyone? My mpg could be 17 and if I park it just goes down pretty quickly within 5 minutes it’ll be at around 9. What’s the reason for this?

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[CorvZ061]

Because the engine is running, using gas, but you’re not moving. So while you’re stopped idle you’re getting 0 miles per gallon.

 

[AnthonyA1234]

Because the engine is running, using gas, but you’re not moving. So while you’re stopped idle you’re getting 0 miles per gallon.

Yea that makes sense I just figured the car would realize this and not mess up my average. Thanks

 

[CorvZ061]

Yea that makes sense I just figured the car would realize this and not mess up my average. Thanks

unless it figures in idle time you won’t have an accurate average. Do you think it doesn’t use gas when your idling?

 

[fast306stang]

17 down to 9 in five minutes seems like a lot. I idle every morning at work for about 25 minutes and it might drop by 1...if I'm pretty well into the tank of gas. If I've just filled up, I'll lose more...like it might go from 23 to 20 or something like that.

 

[CorvZ061]

17 down to 9 in five minutes seems like a lot. I idle every morning at work for about 25 minutes and it might drop by 1...if I'm pretty well into the tank of gas. If I've just filled up, I'll lose more...like it might go from 23 to 20 or something like that.

It just depends on how many miles are on that tank, if you have 200 miles on the tank it won’t move much. If you have 5 it’ll move a lot.

 

[ice445]

Yeah, unless the running average is pretty short, as in you just reset it recently it shouldn't drop that fast.

 

[fast306stang]

It just depends on how many miles are on that tank, if you have 200 miles on the tank it won’t move much. If you have 5 it’ll move a lot.

Yes, that's basically what I was getting at lol...

 

[Zelek]

If you want real MPG, calculate it at the pump. That's where you'll get the most accurate numbers.

Fuelly is good for tracking something like this if that's your thing.

 

[Andrew@Lethal]

Does this happen to anyone? My mpg could be 17 and if I park it just goes down pretty quickly within 5 minutes it’ll be at around 9. What’s the reason for this?

When you are stopped at idle you are not moving while the engine is using fuel. So 0 miles per gallon at idle.

 

[ALLSTOCK]

does mpg go negative if you drive in reverse?

 

[Geosh]

does mpg go negative if you drive in reverse?

Haven’t you seen Ferris Bueller? No, it doesn’t work that way. :-)

 

[EFI]

I just figured the car would realize this and not mess up my average.

That's why it's called and average, because it averages all your driving and gives you a number.

If you just want fancy MPG to brg about, then go to the top of a hill, reset your MPG and coast downhill. Instant 100mpg.

 

[Avispa]

I hate how the MPG drops when I stomp on the gas......lol

 

[Mr. Met]

I guess most people disagree but I always thought it was stupid the car keeps calculating mpg while stopped, at least in park. I would hope people understand you are getting 0 mpg while in park with the engine on. I want to know my mpg while actually driving. Especially in the winter, I often have the car ruining while stopped.

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